src/basic/exec-util.c

   1 /***
   2   This file is part of systemd.
   3
   4   Copyright 2010 Lennart Poettering
   5
   6   systemd is free software; you can redistribute it and/or modify it
   7   under the terms of the GNU Lesser General Public License as published by
   8   the Free Software Foundation; either version 2.1 of the License, or
   9   (at your option) any later version.
  10
  11   systemd is distributed in the hope that it will be useful, but
  12   WITHOUT ANY WARRANTY; without even the implied warranty of
  13   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  14   Lesser General Public License for more details.
  15
  16   You should have received a copy of the GNU Lesser General Public License
  17   along with systemd; If not, see <http://www.gnu.org/licenses/>.
  18 ***/
  19
  20 #include <dirent.h>
  21 #include <errno.h>
  22 #include <sys/prctl.h>
  23 #include <sys/types.h>
  24 #include <unistd.h>
  25
  26 #include "alloc-util.h"
  27 #include "conf-files.h"
  28 #include "exec-util.h"
  29 #include "hashmap.h"
  30 #include "macro.h"
  31 #include "process-util.h"
  32 #include "set.h"
  33 #include "signal-util.h"
  34 #include "stat-util.h"
  35 #include "string-util.h"
  36 #include "strv.h"
  37 #include "util.h"
  38
  39 /* Put this test here for a lack of better place */
  40 assert_cc(EAGAIN == EWOULDBLOCK);
  41
  42 static int do_spawn(const char *path, char *argv[], pid_t *pid) {
  43         pid_t _pid;
  44
  45         if (null_or_empty_path(path)) {
  46                 log_debug("%s is empty (a mask).", path);
  47                 return 0;
  48         }
  49
  50         _pid = fork();
  51         if (_pid < 0)
  52                 return log_error_errno(errno, "Failed to fork: %m");
  53         if (_pid == 0) {
  54                 char *_argv[2];
  55
  56                 assert_se(prctl(PR_SET_PDEATHSIG, SIGTERM) == 0);
  57
  58                 if (!argv) {
  59                         _argv[0] = (char*) path;
  60                         _argv[1] = NULL;
  61                         argv = _argv;
  62                 } else
  63                         argv[0] = (char*) path;
  64
  65                 execv(path, argv);
  66                 log_error_errno(errno, "Failed to execute %s: %m", path);
  67                 _exit(EXIT_FAILURE);
  68         }
  69
  70         log_debug("Spawned %s as " PID_FMT ".", path, _pid);
  71         *pid = _pid;
  72         return 1;
  73 }
  74
  75 static int do_execute(char **directories, usec_t timeout, char *argv[]) {
  76         _cleanup_hashmap_free_free_ Hashmap *pids = NULL;
  77         _cleanup_strv_free_ char **paths = NULL;
  78         char **path;
  79         int r;
  80
  81         /* We fork this all off from a child process so that we can
  82          * somewhat cleanly make use of SIGALRM to set a time limit */
  83
  84         (void) reset_all_signal_handlers();
  85         (void) reset_signal_mask();
  86
  87         assert_se(prctl(PR_SET_PDEATHSIG, SIGTERM) == 0);
  88
  89         r = conf_files_list_strv(&paths, NULL, NULL, (const char* const*) directories);
  90         if (r < 0)
  91                 return r;
  92
  93         pids = hashmap_new(NULL);
  94         if (!pids)
  95                 return log_oom();
  96
  97         STRV_FOREACH(path, paths) {
  98                 _cleanup_free_ char *t = NULL;
  99                 pid_t pid;
 100
 101                 t = strdup(*path);
 102                 if (!t)
 103                         return log_oom();
 104
 105                 r = do_spawn(t, argv, &pid);
 106                 if (r <= 0)
 107                         continue;
 108
 109                 r = hashmap_put(pids, PID_TO_PTR(pid), t);
 110                 if (r < 0)
 111                         return log_oom();
 112
 113                 t = NULL;
 114         }
 115
 116         /* Abort execution of this process after the timout. We simply
 117          * rely on SIGALRM as default action terminating the process,
 118          * and turn on alarm(). */
 119
 120         if (timeout != USEC_INFINITY)
 121                 alarm((timeout + USEC_PER_SEC - 1) / USEC_PER_SEC);
 122
 123         while (!hashmap_isempty(pids)) {
 124                 _cleanup_free_ char *t = NULL;
 125                 pid_t pid;
 126
 127                 pid = PTR_TO_PID(hashmap_first_key(pids));
 128                 assert(pid > 0);
 129
 130                 t = hashmap_remove(pids, PID_TO_PTR(pid));
 131                 assert(t);
 132
 133                 wait_for_terminate_and_warn(t, pid, true);
 134         }
 135
 136         return 0;
 137 }
 138
 139 void execute_directories(const char* const* directories, usec_t timeout, char *argv[]) {
 140         pid_t executor_pid;
 141         int r;
 142         char *name;
 143         char **dirs = (char**) directories;
 144
 145         assert(!strv_isempty(dirs));
 146
 147         name = basename(dirs[0]);
 148         assert(!isempty(name));
 149
 150         /* Executes all binaries in the directories in parallel and waits
 151          * for them to finish. Optionally a timeout is applied. If a file
 152          * with the same name exists in more than one directory, the
 153          * earliest one wins. */
 154
 155         executor_pid = fork();
 156         if (executor_pid < 0) {
 157                 log_error_errno(errno, "Failed to fork: %m");
 158                 return;
 159
 160         } else if (executor_pid == 0) {
 161                 r = do_execute(dirs, timeout, argv);
 162                 _exit(r < 0 ? EXIT_FAILURE : EXIT_SUCCESS);
 163         }
 164
 165         wait_for_terminate_and_warn(name, executor_pid, true);
 166 }